Sugar the Reason Diabetics Have a Higher Risk of Aggressive Cancers

Written by David Heitz on August 5, 2013

Insulin-starved cancer cells still find ways to grow, and sugar in your diet is a likely culprit.

New research offers the answer to a mystery that has perplexed scientists for decades: How do cancerous tumors in diabetics and others with metabolic problems like obesity grow even when their cells are starving for energy?

A study published by doctors at the Icahn School of Medicine at Mount Sinai Medical Center in New York City shows that when dietary sugar combines with cancer genes “all of a sudden you have a tumor that is a sink,” Dr. Ross Cagan, lead author of the study, told Healthline.

What's more, Cagan has found a way to combat the problem, at least in fruit flies.

Cancer Cells Bypass Insulin Roadblocks

The report, published last week in the journal Cell, outlines Cagan's findings. Most importantly, it shows that even though a cancer cell's insulin pathways don't work in diabetics, cancerous tumors get around that roadblock and trigger the insulin receptors regardless. As a result, cancerous tumors metastasize and spread to other parts of the body.

Cagan, a professor of developmental and regenerative biology, explained that Ras and Src, “classic human cancer genes,” can act similarly in fruit flies. When dietary sugar combines with these genes, it activates a pathway that allows the cells to take in sugar. “Tumors love sugar,” Cagan said. “It helps them grow.”

The diabetes-cancer link is most often found in people with cancers of the pancreas, breast, liver, or colon, Cagan said.

Hope for Human Patients?

In what could be a monumental discovery if proven true in humans, Cagan found that medicating the flies with arcabose, AD81, and pyrvinium reduced tumor size and progression. “Importantly, we showed that any of these drugs alone was not effective, but the cocktail worked nicely to dramatically reduce the tumor and extend the fly's lifespan,” he said.

Arcabose is approved for patient use, but AD81 and pyrvinium are experimental, Cagan said.

More questions still need to be answered. “We don't entirely understand how cells become insulin resistant, but we know that chronic high circulating levels of sugar in our blood leads to cells becoming more and more resistant to circulating insulin,” Cagan said. “Eventually, this can lead to metabolic syndrome and even diabetes.”

Cagan is already doing research to determine whether the same chain of events he uncovered in fruit flies also occurs in insulin-resistant humans. If so, he hopes to create compounds that will solve the problem for people as well. “We'll nail it,” he said.

Lifestyle Changes Can Help

There are changes people can make to improve their health and lifespans, even if they are suffering from cancer and diabetes.

Karen Collins, a nutrition adviser with the American Institute for Cancer Research and author of the report “The Diabetes-Cancer Connection,” told Healthline that people with diabetes need to understand that they face a higher risk of cancer.

“Research now shows that although there is a genetic link that increases risk of both type 2 diabetes (which accounts for the vast majority of diabetes cases in the U.S.) and also a genetic link to cancer risk, lifestyle still has very powerful effects influencing if or when someone develops the disease," Collins said. "What has increasingly come to light in recent years is that many of the same lifestyle choices that increase the risk of type 2 diabetes also increase the risk of cancer.”

Cagan said although there has been a “raging debate” about how patients should adapt their diets if they are at risk for diabetes and cancer, one thing is clear: “Now the pendulum has clearly swung to sugar. Everyone is concerned about sugar, and they should be.”